NSW coast home to 250 young great white sharks

Up to 250 juvenile great white sharks are living off the NSW coast and spending a lot of time off beaches in depths of one to five metres, CSIRO research has found.

Tagged great whites have been tracked swimming along the coast from Lake Macquarie to Seal Rocks. These sharks are ''abundant along a section of coastal waters in the Port Stephens region'' from about September to January each year, the study says.

The sharks are residing along three beaches: northern Stockton, which is south of the Port Stephens estuary, and Bennetts (also known as Hawks Nest Beach) and Mungo Brush to its north. Satellite tracking showed juvenile white pointers occupied waters from inshore to depths of 120 metres, about 25 kilometres offshore.

''They spend a significant amount of time in the surf zone in water depths of one to five metres, where they are readily observable and frequently encountered by the public,'' a CSIRO report said.

Research in 2010 and 2011, based on tagging and monitoring, estimated the sharks spend ''an average of 36.5 per cent'' of their time off Port Stephens in ''near-shore waters including the surf zone''.

In 2012-13, great whites were recorded spending 20 per cent of their time in the surf zone.

''This study provides further confirmation the Port Stephens region is a key nursery area for juvenile white sharks in eastern Australia,'' the report said.

A CSIRO statement said the ''frequency of encounters between people and sharks can be high'' in the area, but the frequency of attacks was ''very low''.

Surf lifesavers said attacks off this coast were rare, but there had been two recent attacks in the port itself, off Jimmys Beach.

CSIRO researcher Barry Bruce said the objectives of the 2007-13 research were to ''determine the survival rate of juveniles and adults and provide estimates of abundance of juveniles''.

The CSIRO said a new project this year would develop techniques for ''a population assessment'' for great white sharks.

''An assessment is necessary to understand whether the species is recovering,'' a statement said. ''The project will advance efforts to halt the decline of marine biodiversity through supporting the recovery of a threatened species, the [great] white shark.''

The CSIRO program at Port Stephens involved tagging great whites and doing aerial surveys.

The sharks were usually 1.8 to 2.6 metres in length. Some were up to 3.5 metres long. The sharks commonly departed the Port Stephens area from December to January.